dsp: q6voice: Adds checks for an integer overflow

there is no check for cvs_voc_pkt[2],when recieves
0xffffffff from ADSP which results in an integer overflow
Fix is to address this.

Change-Id: Ie935dd8823981ec260d77f5117f4ef0b0fc08f60
Signed-off-by: Ramireddy KrishnaKanth Reddy <quic_ramikris@quicinc.com>